Superdiffusion in dispersions of active colloids driven by an external field and their sedimentation equilibrium

Yen-Fu Chen, Hsien-Hung Wei, Yu-Jane Sheng, and Heng-Kwong Tsao
Phys. Rev. E 93, 042611 – Published 25 April 2016

Abstract

The diffusive behaviors of active colloids with run-and-tumble movement are explored by dissipative particle dynamics simulations for self-propelled particles (force dipole) and external field-driven particles (point force). The self-diffusion of tracers (solvent) is investigated as well. The influences of the active force, run time, and concentration associated with active particles are studied. For the system of self-propelled particles, the normal diffusion is observed for both active particles and tracers. The diffusivity of the former is significantly greater than that of the latter. For the system of field-driven particles, the superdiffusion is seen for both active particles and tracers. In contrast, it is found that the anomalous diffusion exponent of the former is slightly less than that of the latter. The anomalous diffusion is caused by the many-body, long-range hydrodynamic interactions. In spite of the superdiffusion, the sedimentation equilibrium of field-driven particles can be acquired and the density profile is still exponentially decayed. The sedimentation length of field-driven particles is always greater than that of self-propelled particles.

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  • Received 1 February 2016
  • Revised 17 March 2016

DOI:https://doi.org/10.1103/PhysRevE.93.042611

©2016 American Physical Society

Physics Subject Headings (PhySH)

Polymers & Soft Matter

Authors & Affiliations

Yen-Fu Chen1, Hsien-Hung Wei2, Yu-Jane Sheng1,*, and Heng-Kwong Tsao3,4,†

  • 1Department of Chemical Engineering, National Taiwan University, Taipei, Taiwan 106, Republic of China
  • 2Department of Chemical Engineering, National Cheng Kung University, Tainan, Taiwan 701, Republic of China
  • 3Department of Physics, National Central University, Jhongli, Taiwan 320, Republic of China
  • 4Department of Chemical and Materials Engineering, National Central University, Jhongli, Taiwan 320, Republic of China

  • *yjsheng@ntu.edu.tw
  • hktsao@cc.ncu.edu.tw

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Issue

Vol. 93, Iss. 4 — April 2016

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